tpp task 2 transmission system impact assesment

European Agency for Reconstruction Pyry-CESI-Terna-Decon

November, 2007

European Agency for Reconstruction

Contract nr 05KOS01/04/005 Studies to support the development of new generation capacities

and related transmission Kosovo UNMIK CONSORTIUM OF PYRY, CESI, TERNA AND DECON

TASK 2

Transmission System Impact Assessment

Studies to support the development of new November, 2007 generation capacities and related transmission Page 2 (164) Task 2, Transmission System Impact Assessment


Disclaimer

While the consortium of Pyry, CESI, TERNA and DECON considers that the information and opinions given in this work are sound, all parties must rely upon their own skill and judgment when making use of it. The consortium members do not make any representation or warranty, expressed or implied, as to the accuracy or completeness of the information contained in this report and assumes no responsibility for the accuracy or completeness of such information. The consortium members will not assume any liability to anyone for any loss or damage arising out of the provision of this report.

The report contains projections that are based on assumptions that are subject to uncertainties and contingencies. Because of the subjective judgments and inherent uncertainties of projections, and because events frequently do not occur as expected, there can be no assurance that the projections contained herein will be realized and actual results may be different from projected results. Hence the results and projections supplied are not to be regarded as firm predictions of the future, but rather as illustrations of what might happen. Parties are advised to base their actions on an awareness of the range of such projections, and to note that the range necessarily broadens in the latter years of the projections.



Table of contents

1 TASK REPORT FOR TASK 2: TRANSMISSION SYSTEM IMPACT ASSESSMENT ...................................................................................................................6

1.1 Assess of the availability of transmission capacity for inter-regional Transfers (Part of Subtask 2.1 of ToR) .............................................................................................................7 1.1.1 History of Energy Exchanges on Kosovo 400 kV transmission system..............................7 1.1.2 Conclusions ..........................................................................................................................8 1.2 Assess the transmission expansion plans and new interconnection projects of SEE transmission network (Part of Subtask 2.1 of ToR) .............................................................9 1.2.1 Development of SEE transmission network.........................................................................9 1.2.2 Development of SEE generation system............................................................................11 1.3 Establishment of Transmission Network Model of SEE (Part of Subtask 2.2 of ToR).....11 1.3.1 SEE national Peak Loads ...................................................................................................14 1.3.2 Substation Loads ................................................................................................................15 1.3.3 Scenarios of Power Exchange ............................................................................................15 1.3.4 Options regarding sites, connection schemes and unit size of the new plant.....................16 1.3.4.1 Connection schemes of the new plant ................................................................................16 1.3.4.2 Options of generation unit size of the new plant................................................................18 1.4 Steady State Analysis of Interconnected Transmission Network (Part of Subtask 2.3 of ToR) ...................................................................................................................................20 1.4.1 Introduction Load flow studies ..........................................................................................20 1.4.2 Analysis of steady-state conditions of the year 2012.........................................................21 1.4.2.1 Network configuration with the 400 kV line Kosovo C (KS) Kashar (AL) ...................22 1.4.2.2 Year 2012 Network configuration without the 400 kV line Kosovo C (KS) - Kashar(AL) .. ............................................................................................................................................28 1.4.2.3 Year 2012 Conclusion........................................................................................................31 1.4.3 Analysis of steady-state conditions of the year 2014.........................................................33 1.4.3.1 Year 2014 Network configuration with the 400 kV line Kosovo C (KS) - Kashar(AL) ..33 1.4.3.2 Year 2014 Network configuration without the 400 kV line Kosovo C (KS) Kashar (AL)........................................................................................................................39 1.4.3.3 Year 2014 Conclusion........................................................................................................42 1.4.4 Analysis of steady-state conditions of the year 2016.........................................................44 1.4.4.1 Year 2016 Option 1 of new TPP Kosovo C: third unit 500 MW.......................................44 1.4.4.2 Year 2016 Option 3 of new TPP Kosovo C: second unit 750 MW ...................................48 1.4.4.3 Year 2016 Conclusion........................................................................................................48 1.4.5 Analysis of steady-state conditions of the year 2018.........................................................50 1.4.5.1 Network configuration without additional reinforcements ................................................50 1.4.5.2 Network configuration with a new 400 kV line Kosovo C (KS) Skopje 4 (MK)...........54 1.4.5.3 Network configuration with a new 400 kV line Kosovo C (KS) Skopje 4 (MK) and with a new 400 kV line Skopje 4 (MK)- Leskovac (SR) - (Nis)(SR)...............................56 1.4.5.4 Year 2018 Conclusion........................................................................................................58 1.4.6 Analysis of steady-state conditions of the year 2020.........................................................59 1.4.6.1 Network configuration without additional reinforcements ................................................59 1.4.6.2 Network configuration with a new 400 kV line Kosovo C (KS) Skopje 4 (MK)...........63 1.4.6.3 Network configuration with a new 400 kV line Skopje 4 (MK)- Leskovac (SR) - (Nis)(SR) ............................................................................................................................64 1.4.6.4 Network configuration with a new 400 kV line Kosovo C (KS) Skopje 4 (MK) and 400 kV line Skopje 4 (MK)- Leskovac (SR) - (Nis)(SR) .................................................66



1.4.6.5 Year 2020 Conclusion........................................................................................................67 1.5 Evaluation of adequacy of Regional transmission System and its Transfer Capability (Part of Subtasks 2.2 and 2.3 of ToR) ................................................................................68 1.5.1 Introduction ........................................................................................................................68 1.5.2 Methodology of computing NTC.......................................................................................70 1.5.3 Definition of Transfer Capabilities of transmission network.............................................71 1.5.3.1 Target year 2012.................................................................................................................72 1.5.3.2 Target year 2014.................................................................................................................75 1.5.3.3 Target year 2016.................................................................................................................78 1.5.3.4 Target year 2018.................................................................................................................79 1.5.3.5 Target year 2020.................................................................................................................82 1.5.3.6 Conclusion..........................................................................................................................88 1.6 Capacity Allocation and Congestion Management (Part of Subtasks 2.1 of ToR)............91 1.6.1 Introduction ........................................................................................................................91 1.6.2 Congestion Management methods in SEE.........................................................................92 1.6.3 Work status of the Coordinated Auctions dry-run simulation in SEE ...............................94 1.6.4 Coordinated Auctioning: A market-base method for transmission capacity allocation in meshed network..................................................................................................................95 1.7 Transient Stability Analysis (Part of the subtask 2.2 of ToR) ...........................................97 1.7.1 Introduction ........................................................................................................................97 1.7.2 Evidence of System Stability .............................................................................................97 1.7.3 Transient simulation Methodology ....................................................................................98 1.7.4 Simulation for Validation of Dynamic Model ...................................................................99 1.7.4.1 Test of dynamic behavior of control devices .....................................................................99 1.7.4.2 Reconstruction of selected emergencies ..........................................................................100 1.7.5 System Disturbance..........................................................................................................102 1.7.6 Year 2012 Transient Stability Analysis ...........................................................................104 1.7.6.1 Option 2 of new plant Kosovo C: Unit size 600 MW......................................................104 1.7.6.2 Option 1 of new plant Kosovo C: Unit size 500 MW......................................................110 1.7.7 Year 2014 Transient Stability Analysis ...........................................................................116 1.7.7.1 Year 2014 Network configuration without the 400 kV line Kosovo C (KS) Kashar (AL) ..........................................................................................................................................116 1.7.7.2 Year 2014 Network configuration with the 400 kV line Kosovo C (KS) Kashar (AL)117 1.7.7.3 Year 2014 Conclusions ....................................................................................................119 1.7.8 Year 2016 Transient Stability Analysis ...........................................................................120 1.7.8.1 Option 1 of new plant Kosovo C: Unit sizes 500 MW ....................................................120 1.7.8.2 Option 3 of new plant Kosovo C: Unit size 750 MW......................................................123 1.7.8.3 Year 2016 Conclusions ....................................................................................................128 1.7.9 Year 2018 Transient Stability Analysis ...........................................................................129 1.7.9.1 Option 1 of new plant Kosovo C: Unit sizes 500 MW ....................................................129 1.7.9.2 Option 3 of new plant Kosovo C: third unit 750 MW .....................................................135 1.7.10 Year 2020 Transient Stability Analysis ...........................................................................141 1.7.10.1 Year 2020 Network configuration without the 400 kV line Kosovo C (KS) Skopje 4 ...... (MK) ..........................................................................................................................................142 1.7.10.2 Year 2020 Network configuration with the 400 kV line Kosovo C (KS) Skopje 4 . (MK) ...........................................................................................................................................144 1.7.10.3 Year 2020 Network configuration with the 400 kV line Nish (SR)-Leskovac (SR) ........ Skopje 5 (MK).................................................................................................................145 1.7.10.4 Year 2020 Conclusions ...................................................................................................146 1.7.11 General Conclusions of Transient Stability .....................................................................147



1.8 Short circuit analysis (Part of the Subtask 2.2 of ToR)....................................................152 1.8.1 Methodology and main assumption .................................................................................152 1.8.1.1 Short circuit calculation Year 2012..................................................................................152 1.8.1.2 Short circuit calculation: Year 2014.................................................................................153 1.8.1.3 Short circuit calculation: Year 2016.................................................................................153 1.8.1.4 Short circuit calculation: Year 2018.................................................................................153 1.8.1.5 Summary of short circuit calculation ...............................................................................153 1.8.1.6 Conclusion........................................................................................................................154 1.9 Cost Estimate of transmission network reinforcements...................................................155 1.10 Recommendations regarding reinforcements of national 220 kV, 110 kV transmission network.............................................................................................................................156 1.11 Recommendations regarding Protection and Equipment specification............................158

REFERENCES...............................................................................................................................159

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1 TASK REPORT FOR TASK 2: TRANSMISSION SYSTEM IMPACT ASSESSMENT

The Terms of reference for the project

Studies to support the development of new generation capacities and related transmission Kosovo UNMIK called for the consultant to significantly increase the level of understanding for the potential electricity market facing any expansion of lignite-fired generation capacity planned for Kosovo. The information to be generated should enhance the knowledge and understanding of the regional electricity market and generate a knowledge base for the Kosovan authorities, the foreseen project lenders and potential investors on which they would be better placed to make decisions regarding future power sector development.

This report on Task 2 does not include the description of the respective consultants methodology and modeling tools. In this respect, we wish to refer materials presented in our tender. However, the consortium members are willing to make their methodology descriptions available to any party or stakeholder making such a request.

The consortium has also refrained from evaluation power export potential to Greece and Italy, in order not to prejudice the position of any prospective investor candidate in the concurrent investor selection process by the Kosovan government.

In this report on Task 2, the report structure does not strictly follows the description of Task 2 in the ToR. The Consultant has followed a more methodological numbering of the chapter based on a relationship of input-output of results between them. Nevertheless the report fully covers all the items of ToR. The internal sectioning and numbering of the report has been limited to number 2, to better reflect the sectioning of Task 2 in the ToR.

Introduction to TASK 2 Scope of work The aim of this activity is to verify the feasibility of national and regional transmission system to deliver the maximum power plant capacity and to identify potential constraints, depending on large unit size, concerning transient stability of the regional system. The analyzed period is 2010 up to 2020.

Specific objectives of this task are:

Assessment of adequacy of the local and regional transmission system taking into consideration the planned reinforcement of the network and assessment of the costs related to improvement of transmission capacity necessary for delivery of the power from new plant to the potential off-taker.

Assessment of unit maximum size based on deterministic reliability analysis and transient stability studies and identifying the possible network reinforcements in order to be fully compliant with technical standards of security and reliability and rules adopted by UCTE.

Development of conceptual design and cost estimates for the new plants interconnection to bulk transmission system.



1.1 Assess of the availability of transmission capacity for inter-regional Transfers (Part of Subtask 2.1 of ToR)

The transmission network of Kosovo power system is a part of the regional interconnected transmission systems and the 400 kV interconnection lines of Kosovo are some of the principal media with a wide regional interest for reliable electric supply and energy exchanges between neighboring power systems of Serbia, Montenegro, Macedonia, Greece, Albania, etc.

The power transactions in the SEE region and exhibit considerable seasonal and daily load variations, with electricity demand being dependent on weather conditions, hydrology and it is reflected as variation of power transits on the main transmission lines.

The existing transmission lines and interconnections between the national power systems of the region permit transactions ranging from 250 MW to 1600 MW, depending on the origin, destination path, and time period.

The inter-regional scheduled transfers have a crucial impact on the loadability of the interconnection lines and, for generation and transmission planning purposes, it is important to consider appropriate levels of power exchanges between SEE countries. Referring to expected network situation up to 2020, the power exchange represents a random and uncertain variable and, in order to assess the availability of the transmission capacity, Consultant has performed a statistical analysis of the recorded power and energy transits on 400 kV transmission network of Kosovo during past period (2000-2006), aiming to definition of a set of inter-regional power transfers to be modeled on simulations as a first step for evaluation of technical performance of the actual, planned and reinforced network.

1.1.1 History of Energy Exchanges on Kosovo 400 kV transmission system The Consultant has performed a statistical analysis of the loadability of the 400 kV lines based on recorded direct measurements of the hourly power flows in interconnection lines. The objective of this part of the study is to investigate, for the period 2000 - 2006, the import-export energy flows of each one of the 400 kV lines in Kosovo and, thus to assess the future trend related to annual electricity volumes that would be traded between Kosovo and potential off-taker of regional utilities.

The present 400 kV interconnection lines of Kosovo power system are:

L407: 400 kV Kosovo B Nish (SR), rated power 1330 MVA and natural transmission capacity 512 MVA;

L437: 400 kV Kosovo B Ribarevina (MN), rated power 1330 MVA and natural transmission capacity 512 MVA;

L420: 400 kV Kosovo B Skopje (MK), rated power 1330 MVA and natural transmission capacity 512 MVA;

A summary of the main figures concerning development of the loadability of the 400 kV lines in Kosovo during the period 2000- 2006, are given in Annex 1.

In Figure Figure 1-1 are illustrated the annual energy wheeling through transmission network of Kosovo, maximum and minimum powers in 400 kV lines during the period 2000-2006.



In Tables A1.1 to A1.7 in Annex 1 are reported statistic data for loadability of the 400 kV lines during the period 2000-2006. During this period he wheeling of energy was significantly increased from North to South, loading the corridor Nish Kosovo Skopje. The daily and annual Load Factors continue to increase showing a trend toward full exploitation of the transfer capability of the corridor.

Figure 1-1 Period 2000-2006 Trend of power and annual electric energy wheeled through Kosovo network

1.1.2 Conclusions Historical data on power transfers realized by 400 kV transmission system of Kosovo show great variations from year to year and the tendency is that the volume of power and energy transfers is increasing year by year.

The loading of interconnection lines depends on the level of electrical energy trades on the region and varies with load growth. All studies dedicated to the SEE region have reached at conclusion that actual inter-country electricity trade is at very low level and the electricity market is not developed to a great extent. Nevertheless the present level of loadability of 400 kV transmission system of Kosovo is quite high and the tendency is towards an increasing of the energy wheeling through Kosovo.



In such conditions it is unlikely that present transmission system can provide the adequate available transfer capabilities for expected electricity exports from the new TPP Kosovo C utilising existing physical paths. In additional, the development of the electricity market in SEE will require more transfer capabilities for energy exchanges among countries.

1.2 Assess the transmission expansion plans and new interconnection projects of SEE transmission network (Part of Subtask 2.1 of ToR)

The Consultant has reviewed all available studies and reports concerning the possible transmission network reinforcements on SEE region. In our study the transmission network reinforcements and interconnections projects of the so called Common Interest Projects have been considered. Consultant has found from different sources, different lists of projects with different time schedules of commissioning of new lines. The most probable projects and the projects in phase of construction or in phase of waiting decision are considered in the study.

In particular the information on development of the regional transmission network considered in the REBIS Generation Investment Study (GIS) has been assessed.

The objective of the revised Generation Investment Study GIS (2007) was the development of a long-term investment plan (2005-2020) for the SEE Region for power generation. It is an updated of the original GIS (2004) where one of the key objectives was also to identify priority investments in main transmission interconnections between the countries and sub-regions that allow optimizing investment requirements in power generation over the study horizon.

Other available documents analyzed by Consultant and related to the expansion of the transmission network in SEE for the period from 2005 to 2020, are given in References.

1.2.1 Development of SEE transmission network The list of present situation (year 2005) of the interconnection lines in South East Europe is given in Table A2.1 in Annex 2. According to GIS study and the WG of UCTE System Development, the current state of the transmission investment planning regarding the projects of interconnection lines within the SEE part as well as projects of internal lines with a regional impact are the following:

Status on the investments which have been decided Table 1-1 Planed interconnection lines in South East Europe Year 2010

Conductors Voltage level Type Size

Transfer Capacity

Total length Interconnection line Interconnected countries

(kV) (mm2) (MVA) kmUgljevik - S. Mitrovica BA - SR 400 ACSR 2x490 1330 79Kashar - Podgorica AL - MN 400 ACSR 2x490 1330 145Maritsa Istok - Filipi BG - GR 400 ACSR 3x400 1715 243Chervena Mogila - Stip BG - MK 400 ACSR 3x490 1330 150Ernestinovo - Pecs (double) HR - HU 400 ACSR 2x490 1330 85Bekescaba - Nadab (Oradea) HU - RO 400 ACSR 2x490 1178 118Florina - Bitola GR - MK 400 ACSR 2x490 1330 38(Filipi) - Kehros - Babaeski GR - TR 400 ACSR 3x400 1715 100



Table 1-2 Planed internal lines in South East Europe Year 2010 Conductors Voltage

level Type Size Transfer Capacity

Total length Internal Lines Country

(kV) (mm2) (MVA) kmLine Subotica 3 - Sombor 3 Serbia 400 ACSR 2x490 1330 56Line Tirana - Elbasan Albania 400 ACSR 2x490 1330 45Line Fier - Vlore Albania 220 ACSR 360 301 26Line Karlovo - Plovdiv Bulgaria 400 ACSR 3x490 1330 60Line Arad - Nadab Romania 400 ACSR 2x490 1330 35Lagada - Fillippi Greece 400 ACSR 3x400 1178 110

Table 1-3 Planed substations in South East Europe Year 2010-2015

Project name Country Time schedule

New 400/110 kV Peja II 3 Substation Kosovo to be completed by the year 2009 New 400/110 kV Ferizaj Substation Kosovo to be completed by the year 2012 New 400/110 kV Sombor 3 Substation Serbia to be completed by the year 2007 New 400/110 kV Jagodina 4 Substation Serbia to be completed by the year 2007 New 400/110 kV Beograd 20 Substation Serbia to be completed by the year 2008 New 400/220/110 kV Tirana 2 Substation Albania to be completed by the year 2008 New 220/110 kV Vlora Substation Albania to be completed by the year 2009 400 kV Nadab connection Substation Romania to be completed by the year 2008 Expansion of 400/110 kV Skopje 5 Substation Macedonia to be completed by the year 2006

Table 1-4 Planed interconnection lines in South East Europe Year 2015

Conductors Voltage levelType Size

Transfer Capacity


(kV) (mm2) (MVA) kmKashar - Kosovo C AL - KS 400 ACSR 2x490 1330 215Skopje - Vranje - (Leskovac) - (Nis) MK - SR 400 ACSR 2x490 1330 192Zemlak - Bitola AL - MK 400 ACSR 2x490 1330 85

Status of investments under discussion or as candidate Table 1-5 Candidate lines in South East Europe Year 2015

Conductors Voltage levelType Size

Transfer Capacity


(kV) (mm2) (MVA) kmKosovo - Skopje KS - MK 400 ACSR 2x490 1330 104Visegrad - Pljevlja BA - MN 400 ACSR 2x490 1330 60Tumbri - Banja Luka HR - BA 400 ACSR 2x490 1330 200Pecs - Sombor HU - SER 400 ACSR 2x490 1330 80Maritsa East - Nea Santa BU - GR 400 ACSR Cirkovce - Hviz SLO- HU 400 ACSR 2x490 1330 erjavinec - Cirkovce HR - SLO 400 ACSR 2x490 1330 Suceava - Balti RO - MD 400 ACSR 2x490 1330 Pcs - Ernestinovo HU - HR 400 ACSR 2x490 1330



Status of investments under study Table 1-6 Project of interconnection lines in South East Europe Year 2015

1.2.2 Development of SEE generation system The Consortium for transmission system modeling has assumed the fifth scenario of the Updated GIS study as the main scenario of generation development plan. The main attributes of this scenario are:

free electricity markets, medium demand growth; medium fuel price development; rehabilitation of existing generation units according to relaxed curves; high electricity import scenario; no major hydro plant construction.

The total capacity of the rehabilitation of TPP in the region for the analyzed period is 4,573 MW and the total new capacity to be constructed (including Kosovo C) is 16,164MW

Table A2.2 in Annex 2 reports the development of the generation plan of this scenario with the list of new and rehabilitated generation units along with time schedule of construction.

1.3 Establishment of Transmission Network Model of SEE (Part of Subtask 2.2 of ToR)

Establishment of computer models for analysis of interconnected transmission system is carried out based on appropriate network model of SEE countries. The planned network configuration over planning period is considered, including all present and planned main transmission lines and other electric facilities.

The REBIS GIS study has analyzed the expansion of the generation system optimized over a 15 year horizon (2005 - 2020) for three scenarios (isolated operation of each power system, regional operation of power systems, market conditions) using the WASP models. Only the third scenario has considered the transfer capabilities of the interconnection lines among the utility systems using the Generation and Transmission Maximization Model (GTMax). In addition to GTMax analysis, a dedicated study was carried out analyzing in more detailed the regional transmission network operation and the SECI Regional Transmission System Model in PSS/E was used.

In our study the Consultant, as a starting point, has considered the same SECI model and associated data for preparation of Regional Transmission System Model. The data

Project name Participation Time schedule 400 kV interconnections from Macedonia to Albania and to Italy

SEETEC / EBRD (BG,MK,AL,IT) Feasibility study ongoing

New 400 kV Line between Serbia - Romania SR - RO Preliminary studies underway Submarine 400 kV cable between Romania and Turkey RO -TR Preliminary studies ongoing Submarine 400 kV cable between Croatia and Italy HR - IT Preliminary studies underway 400 kV Line Zrenjanin - Timisoara SR - RO Preliminary studies under preparation New 400 kV interconnection between Croatia and Bosnia-Herzegovina HR - BA Preliminary studies under preparation



bases of SPIRA and SICRE softwares that are used in system analysis, have been interfaced with data base of PSS/E model.

The configuration of 400 kV, 220 kV and for some countries also 150/110 kV, of each national transmission system has been considered.

Considering the particularity of Kosovo transmission network as a part of an interconnected regional network, the dynamic performance simulations have been performed while operating in interconnection mode. In particular, the disturbances in dynamic simulation are applied in 400 kV interconnection lines, which affect in a sensible way the critical clearing times and, consequently, the stability of the rotors.

Mathematic model of Kosovo transmission system includes the entire 400 kV, 220 kV and 110 kV transmission networks. In the model the loads are represented on the 110 kV busbars of each distribution substation.

The mathematical model of the transmission network of the SEE interconnected system includes the equivalent multipole of UCTE and CENTREL together with Austria and Ukraine. The following national power systems are considered in detail till the level of 400 kV:

Hungarian power system. The main 400 kV and 220 (150/110) kV transmission systems of following countries are considered:

Albanian power system; Bosnian power system; Bulgarian power system; Croatian power system; Greek power system; Macedonian power system; Montenegro power system; Romanian power system; Serbia power system; Slovenian power system; Turkish power system. The main parameters of the mathematical model of the transmission network of SEE are reported in



Table 1-7.

The Base Cases of system configuration for each horizon year, 2012, 2014, 2016, 2018 and 2020 of the interconnected systems in SEE region have been prepared and stored into computer data base.

Network models appropriate for static studies have been applied for representing the external networks of UCTE and Ukraine.



Table 1-7 Parameters of the Transmission Network Model year 2020 Parameters of the Transmission Network Model

System Substations Nodes Lines Generators Transformers Speed Governors Voltage

Regulators Albania 85 126 130 115 63 26 36Kosovo 49 70 69 74 29 12 13Bosnia 185 247 252 209 73 30 42Bulgaria 506 662 744 625 163 58 137Croatia 190 274 290 242 100 39 65Greece 759 992 910 860 260 86 106Macedonia 96 127 134 121 34 19 22Montenegro 26 44 30 35 21 6 11Romania 828 1,072 1,171 905 267 81 132Serbia 277 377 400 284 121 60 68Slovenia 139 209 224 174 79 47 63UCTE 98 115 79 92 19 31 32Hungary 58 98 49 123 58 22 32Turkey 718 1,106 1,043 1,656 774 0 682UKRAINA 3 3 0 6 0 3 3CENTRAL 3 3 0 4 0 2 2SEE 4,020 5,525 5,525 5,525 2,061 522 1,446

1.3.1 SEE national Peak Loads The demand and particularly the peak power forecasts for each country in SEE, except Kosovo, prepared in REBIS GIS study have been used for load modelling during the period 20010-2020. We have used the PwC [1] central case, Case 2. Table A2.3 in Annex 2 reports the peak power forecasts in SEE. The minimum peaks are forecasted using information from annual reports for SEE Power Utilities

The forecasted national peaks corresponding to winter and summer time in year 2005, and horizon years 2010, 2015 and 2020 are given in Table 1-8.

In Tables A2.4 and A2.5 of the Annex 2 are reported the peak load and minimum load in the model of the transmission network of SEE system.

The peak of SEE interconnected system is defined as the sum of peak power of individual countries, i.e.: Albania, Kosovo, Bosnia and Herzegovina, Bulgaria, Croatia, Greece, Macedonia, Montenegro, Romania and Serbia Table 1-8 Peak development in SEE region

2005 2010 2015 2020 Winter Summer Winter Summer Winter Summer Winter SummerCountries

MW MW MW MW MW MW MW MW Albania 1.484 1.316 1.652 1.440 1.989 1.703 2.645 2.246Kosovo 1.030 563 1.154 694 1.270 824 1.377 969Bosnia 1.863 1.121 2.076 1.250 2.410 1.451 2.855 1.719Bulgaria 6.383 5.061 6.482 5.379 7.025 5.752 7.340 6.176Croatia 2.817 1.696 3.290 1.909 3.838 2.119 4.448 2.354Greece 9.000 9.837 11.102 12.134 12.705 13.849 14.027 15.290Macedonia 1.360 819 1.373 827 1.607 967 1.946 1.171Montenegro 711 584 725 596 737 637 787 679Romania 7.372 4.503 7.950 4.886 9.234 5.675 11.418 7.017Serbia 5.957 3.958 5.993 3.981 6.393 4.242 6.745 4.472



1.3.2 Substation Loads The individual substation peak loads for each power system are calculated for each horizon year based on total system peak power forecast, regional peak power forecasts and actual regional peak load profiles..

In order to identify the minimum hour within the two characteristic days, there are used the forecasted daily load curves for each target years, 2010, 2015 and 2020.

The active and reactive loads at HV substation level for characteristic hours have been computed based on forecasted national peak, projection coefficients, national load profiles and power factor of individual load.

The results of some countries near Kosovo for some selected years are reported in Annex 2 in Tables A2.6 to A2.13. The substation load forecast related to peak and light load conditions are stored in SPIRA database.

1.3.3 Scenarios of Power Exchange Inter-regional, North South and East West power exchanges scenarios have been developed for each target year and for pear and light load conditions. Based on results of REBIS GIS study of the future generation development of power systems in SEE and the results of SECI model and data concerning Regional Transmission System Model Region, we have prepared and implemented in the transmission-generation model ten bulk transit scenarios composed by power transfers from north to south, east to west and south to north.

For each target years is prepared a table of bilateral transactions between national power systems that represents a set of power flows in transmission interconnected network to be superimposed to the expected export from Kosovo in a analyzed year. The selected Exchange Scenarios consider an increase of the total amount of power transfer inside the region (simultaneous transfers) as follows:

Expected total power transits in 2012 in peak condition of about 3350 MW; Expected total power transits in 2013 in light condition of about 2300 MW; Expected total power transits in 2014 in peak condition of about 2700 MW; Expected total power transits in 2015 in light condition of about 2200 MW; Expected total power transits in 2016 in peak condition of about 3150 MW; Expected total power transits in 2017 in light condition of about 2150 MW; Expected total power transits in 2018 in peak condition of about 3600 MW; Expected total power transits in 2019 in light condition of about 2350 MW; Expected total power transits in 2020 in peak condition of about 3600 MW; Expected total power transits in 2020 in light condition of about 2450 MW.



1.3.4 Options regarding sites, connection schemes and unit size of the new plant

1.3.4.1 Connection schemes of the new plant The three different alternatives for the new site of the TPP Kosovo C determine three different variants for the connection of the plant to the transmission network of Kosovo system.

Site 1 Near existing TPP Kosovo A. The single line diagram is reported in Figure 1-2. The 400 kV busbars are connected with a double line to 400 kV busbars of Kosovo B and the 220 kV of the new plant can be considered as extension of the existing 220 kV busbars of Kosovo A.

The proposed reiforcement of the local transmission network include: Two 400 MVA autotransformers 400/220 kV installed in Kosovo C TPP,

increasing by 30% the total transfer capacity between 400 kV and 220 kV networks.

Two 220 kV lines connecting the 220 kV busbars of new TPP Kosovo C with existing TPP Kosovo B

To improve the reliability of the supply and to optimise the power flows it is proposed to reallocate the double line 220 kV of Pristina 4 from 220 kV busbars of Kosovo B to 220 kV busbars of new Kosovo C

Figure 1-2 Variant 1 for the new site of the TPP Kosovo C

Site 2 Expansion to the north of plant TPP Kosovo B. The single line diagram is reported in Figure 1-3. The 400 kV and the 220 kV busbars of the new plant can be considered as extension of the existing busbars of Kosovo B.

The proposed reiforcement of the local transmission network include: Two 400 MVA autotransformers 400/220 kV installed in Kosovo C TPP,

increasing by 30% the total transfer capacity between 400 kV and 220 kV networks.




To improve the reliability of the supply and to optimise the power flows it is proposed to reallocate the double line 220 kV of Pristina 4 from 220 kV busbars of Kosovo B to 220 kV busbars of new Kosovo C


Site 3 Area in the north-eastern corner of the Sibovc field in Bivolak. The single line diagram is reported in Figure 1-4. The 400 kV and the 220 kV busbars of the new plant are connected with double lines to the existing busbars of Kosovo B.


The proposed reiforcement of the local transmission network include:



Two 400 MVA autotransformers 400/220 kV installed in Kosovo C TPP, increasing by 30% the total transfer capacity between 400 kV and 220 kV networks.


To improve the reliability of the supply and to optimise the power flows it is proposed to reallocate the 220 kV interconnection line Besiana (KS)-Krushevac(SR) from 220 kV busbars of Kosovo B to 220 kV busbars of new Kosovo C

1.3.4.2 Options of generation unit size of the new plant

In our investigation for the determination of the maximum unit size, there are considered different sizes of individual generation units of new power plant assuming as candidate the unit size of 340 MW, 500 MW, 600 MW and 750MW. Three different options of composition of the new 2000 MW TPP Kosovo C are analyzed:

Option 1: 4 units 500 MWnet. Option 2: 4 units 600 MWnet Option 3: 1 unit 500 MWnet and 2 units 750 MWnet

1. Unit size 500 MW technical data The technical data of the analyzed generation unit 500 MWnet are:

Generator Rating: 623 MVA Nominal active power: 530 MW Net active power: 500 MW Minimum operating level: 250 MW Nominal power factor: 0.85 Nominal voltage: 24kV Generator subtransient impedance xd: 0.24 Generator transient impedance xd: 0.38 Generator impedance xd: 2.56 Unit inertia H: 1.8sec The technical data of the step-up transformer are:

Transformer Rating: 625 MVA Nominal voltage primary winding: 410 kV Nominal voltage secondary winding: 24 kV


Generator Rating: 742 MVA Nominal active power: 630 MW Net active power: 600 MW Minimum operating level: 300 MW Nominal power factor: 0.85 Nominal voltage: 24kV



Generator subtransient impedance xd: 0.24 Generator transient impedance xd: 0.38 Generator impedance xd: 2.56 Unit inertia H: 1.8sec The technical data of the step-up transformer are:

Transformer Rating: 750 MVA Nominal voltage primary winding: 410 kV Nominal voltage secondary winding: 24 kV


Generator Rating: 953 MVA Nominal active power: 810 MW Net active power: 750 MW Minimum operting level: 450 MW Nominal power factor: 0.85 Nominal voltage: 24kV Generator subtransient impedance xd: 0.2 Generator transient impedance xd: 0.36 Generator impedance xd: 2.5 Unit inertia H: 2sec The technical data of the step-up transformer are:

Transformer Rating: 960 MVA Nominal voltage primary winding: 410 kV Nominal voltage secondary winding: 24 kV Voltage regulators and excitation systems The block diagram and the parameters of the type of voltage regulator and excitation system that have been used are given in Annex 5.

Governors control system The block diagram and the parameters of the type of governor control system that is implemented in the Data Base for the new unit is given in Annex 5.



1.4 Steady State Analysis of Interconnected Transmission Network (Part of Subtask 2.3 of ToR)

1.4.1 Introduction Load flow studies Full active and reactive power load-flow calculations have been performed in order to correctly simulate the steady-state conditions of the transmission system assessing the ability of transmission system to deliver the electric power to load centers and imported countries under a wide variety of system operating conditions.

The aim of the study is the evaluation of the overall voltage profile of the transmission network, active and reactive flows on transmission lines and transformers, bus voltage magnitudes and phase angles, line currents, line losses and other related steady-state variables.

The generation and transmission systems were modeled in detail till to substations busbars where equivalent loads represent the distribution system.

The objectives of the load flow studies were:

To detect present weaknesses of the operating conditions identifying any overloads and excesses of the thermal limits of components, large voltage deviations, high losses in the transmission facilities, etc.;

To constitute a set of base cases for adequacy analysis to be compared with those in which the possible transmission improvements are to be simulated, in order to evaluate the benefits of interconnections upgrading towards the efficiency.

To constitute a set of base cases for calculation of transfer capability of the forecasted operation of the interconnected transmission network under a specific set of assumed operating conditions that include introduction of new generation capacities, new element of the network and development of electricity demand.

To constitute a set of base cases for transient stability analysis in order to assess the impact of introduction of new power plant to the dynamic behaviors of the regional system and to detect any constrain to power exports from point of view of fulfillment of technical criteria of dynamic stability.

The analysis of the load flows has considered three variants of connection to the grid and three options of unit size of the new TPP Kosovo C.

The target years of the load flow studies are 2012, 2014, 2018 and the horizon year 2020 according to the expected entrance in operation of individual generation units.

For options 1 and 2 of new plant it is assumed the following time schedule of construction of the new plant:

first 500 MW (600MW) unit in operation in 2012 second unit in operation in 2014 third unit in operation in 2016 fourth unit in operation in 2018

For the option 3 of new plant, the first 500MW unit is considered in operation in 2012, the second 750MW unit in 2016 and the last 750 MW unit in 2018.



1.4.2 Analysis of steady-state conditions of the year 2012 The year 2012 was assumed as the year when the first unit of new TPP Kosovo C will be put into operation.

The load flow calculation was carried out based on the projected peak and light load conditions and network configuration in 2012.

System configuration The corresponding configuration of 400 kV, 220 kV, and 150/110 kV of each national transmission system has been considered. Load flow analyses were performed for the three Variants of the connection of TPP Kosovo C in transmission network.

In particular, based on information for the development of SEE transmission network, the following new 400 kV interconnection lines, that have a major impact on power transits, are assumed in operation in 2012:

New 400 kV line Kashar (AL) Podgorica (MN);

New 400 kV line Stip (MK) Chervena Mogila (BG);

New 400 kV line Florina (GR) Bitola (MK); Based on the findings of other studies and the Task 1 of this project, the Consultant has found that the role of a new 400 kV line Kosovo C (KS) Kashar (AL) is crucial for the purpose of this project having in mind that Albania is one of the main candidate as off-taker, so it is assumed that construction of this line can be anticipated and the line should be in operation at the same time with the first unit of Kosovo C. Nevertheless there are analyzed two variant:

New 400 kV line Kosovo C (KS) Kashar (AL) is in operation in 2012;

New 400 kV line Kosovo C (KS) Kashar (AL) is not in service in 2012; The KOSTT has provided the data of the planned configuration of Kosovo transmission network (220kV and 110 kV). Compare to the actual configuration many new substation and network reinforcements are introduced into transmission and sub-transmission network. In the following, the most important new elements in service in 2012 are listed:

New 400/110 kV substation of Peja 3 with transformer capacity 300 MVA; New 220/110 kV substation of Ferizaj 2 with transformer capacity 150 MVA; New 110 kV substations of Pristina 6, Shtime, Malisheva, Rahovec and

Mitrovica; New 110 kV line Pristina 4 Pristina 6; New 110 kV line Lipian Shtime; New 110 kV line Peja 3 Klina; New 110 kV line Peja 3 Istok, New 110 kV line Suhareka- Malisheva; New 110 kV line Malisheva Rahovec; New 110 kV line Rahovec Gjakove.

The introduction of two substations (Peja 3 and Ferizaj 2) together with reinforcement of the north-west part of 110 kV network, has resolved many problems related to reliability of the local network and the voltage profiles in that area.



1.4.2.1 Network configuration with the 400 kV line Kosovo C (KS) Kashar (AL)

1.4.2.1.1 Peak load conditions Generation Dispatch Power dispatch generation units in Kosovo (gross generation) for the peak load conditions is given in Table 1-9. Table 1-9 Winter 2012 Generation dispatch in Kosovo

Pg Qg Power Plant MW Mvar

Ujmani 32 16Kosovo A1 36.5 24Kosovo A3 126 91Kosovo A4 166 94Kosovo A5 166 94Kosovo B1 300 76Kosovo B2 300 76Kosovo C1 530 104Total 1,657 574

Power Exchange Scenarios The scenario of power exchanges in winter peak condition between SEE countries is reported in Table 1-10. Table 1-10 Year 2012 Power Exchanges Scenario in winter peak in SEE

Kosovo BiH Bulgaria Romania Serbia UCTE Total Import\Export MW MW MW MW MW MW MW

Albania 300 100 400Kosovo 0

Greece (& Italy) 300 200 500Macedonia 150 100 250

Montenegro 100 50 50 200Serbia 200 200

Croatia & Slovenia 100 300 400 1,000 1,800Total 300 200 800 900 150 1,000 3,350

Load flow in normal conditions The network was analyzed from point of view of line and equipment loadings, accepted voltage levels, presence of eventually bottlenecks, excessive and unjustified losses, eventually violation of generation capability limits (especially reactive), etc.

The complete analysis of N situations has been carried out for peak load conditions. No line or transformer overloads have been detected and the voltage profile is within normal limit values. Some main results are presented in



Table 1-11 and Table 1-12 for Kosovo power system.



Table 1-11 Year 2012 Peak load condition: Energy Exchanges Transit Losses Active

Power Reactive Power Active Reactive Power Supply

(MW) (MVAr) (MVAr) (MVAr) Generation Kosovo 1,657 595 Exchange with Albania 138.0 -40.6 1.1 -34.3 Exchange with Serbia -69.6 61.6 0.6 -21.2 Exchange with Macedonia 100.5 14.5 0.1 -16.4 Exchange with Montenegro 120.2 -52.1 0.2 -14.6 Total Exchange 289.1 -16.6 2.0 -86.3

Table 1-12 Year 2012 Peak load condition: Power Losses

Variant 1 Variant 2 Variant 3 P Q P Q P Q Power Losses

(MW) (MVAr) (MW) (MVAr) (MW) (MVAr) Total Losses of 400 kV lines 3.0 -68.4 3.0 -64.0 2.9 -67.8Total Losses of 220 kV lines 2.8 -7.9 2.9 -11.6 2.9 -9.0Total Losses of 110 kV lines 16.1 17.7 16.1 17.8 16.0 17.2Total transmission line Losses 21.9 -58.6 22.0 -57.8 21.8 -59.6Total Transformer Losses 9.9 266.7 9.9 266.4 9.9 264.7 Total Losses of Transmission Network 31.8 208.1 31.9 208.6 31.6 205.2

Annex 3 shows the results of load flow calculations. The voltage profile and power flows in Kosovo transmission network and in the main 400 kV lines of the regional transmission network are illustrated in Figures A3.1 to A3.3 for each variant of connection of new plant, and in Figure A3.4 in Annex 3.

Figure 1-5 shows the active power flows in the main interconnection lines of SEE transmission network and the total import / export of each country.

1.4.2.1.2 Light load conditions



Generation Dispatch Table 1-13 reports the generation dispatch (gross generation) for the Kosovo system for the light load conditions. Table 1-13 Summer 2013 Generation dispatch in Kosovo

Figure 1-5 Year 2012 Power transits in SEE network during peak load condition.

Power Exchange Scenarios The scenario of power exchanges in summer light load condition between SEE countries is reported in Table 1-14. Table 1-14 Year 2013 Power Exchanges Scenario in summer minimum in SEE


Albania 200 200Kosovo 0

Greece (& Italy) 300 200 400 900Macedonia 100 100

Montenegro 100 50 150Serbia 100 200 300

Croatia & Slovenia 100 150 150 250 650Total 600 100 550 750 50 250 2,300

Load flow in normal conditions


Ujmani 8 7Kosovo B1 260 -8Kosovo B2 260 -8Kosovo C1 520 -29Total 1,048 -38



The load flow calculation was carried out based on the projected minimum demand and network configuration in 2012.

The complete analysis of N situations has been carried out for light load conditions. No line or transformer overloads have been detected and the voltage profile is within normal limit values. Some main results are presented in .

and Table 1-16 for Kosovo power system.



Table 1-15 Year 2013 Light load condition: Energy Exchanges Transit Losses Active

Power Reactive Power Active Reactive Power Supply

(MW) (MVAr) (MVAr) (MVAr) Generation Kosovo 1,048 -38 Exchange with Albania 228.6 -35.7 0.6 -41.7 Exchange with Serbia -41.4 -34.6 0.1 -25.0 Exchange with Macedonia 273.7 23.8 0.2 -15.4 Exchange with Montenegro 140.2 -40.1 0.3 -15.6 Total Exchange 601.1 -86.6 1.2 -97.7

Table 1-16 Year 2013 Light load condition: Power Losses


(MW) (MVAr) (MW) (MVAr) (MW) (MVAr) Total Losses of 400 kV lines 1.6 -84.8 1.6 -79.1 1.6 -82.9Total Losses of 220 kV lines 0.8 -23.2 0.8 -25.0 0.9 -25.9Total Losses of 110 kV lines 1.4 -29.8 1.7 -30.8 1.6 -30.9Total transmission line Losses 3.7 -137.7 4.0 -134.9 4.1 -139.7Total Transformer Losses 4.8 108.6 4.9 110.7 4.9 109.7

Total Losses of Transmission Network 8.5 -29.2 8.9 -24.2 8.9 -29.9

In Figure 1-6 are shown the active power flows in the main interconnection lines of SEE transmission network and the total import / export of each country.

Figure 1-6 Year 2013 Power transits in SEE network during light load condition.



1.4.2.2 Year 2012 Network configuration without the 400 kV line Kosovo C (KS) - Kashar(AL)

1.4.2.2.1 Peak load conditions Load flow in normal conditions The voltage profile and power flows in Kosovo transmission network and in the main 400 kV lines of the regional transmission network are illustrated in Figures A3.5 and in Figure A3.6 in Annex 3. A summary of load flow calculation and comparison with the results of case where the 400 kV line is in operation, is reported in the following.

The power exchanges with neighboring countries are reported in Table 1-17 and the power flows in the main interconnection lines of SEE transmission network and the total import / export of each country are given in Figure 1-7. It can be observed that the power transited by the line is now equally shared by the 400 kV lines of Montenegro and Macedonia.

Transmission power losses of Kosovo and overall transmission losses of the modeled SEE system are reported in Table 1-18 and Table 1-19. Comparing the results of two cases can be seen that the presence of the line has decreased the power losses for Kosovo and for all the region respectively by 1.6 MW and 8.4 MW. Table 1-17 Year 2012 Peak load condition : Energy Exchanges

With 400kV KS-AL Without 400kV KS-AL P Q P Q Power Exchanges

(MW) (MVAr) (MW) (MVAr) Exchange with Albania 137.0 -38.4 -45.5 -64.6 Exchange with Serbia -71.9 48.3 -20.8 32.8 Exchange with Macedonia 101.7 6.2 169.4 -8.6 Exchange with Montenegro 122.5 -50.0 185.1 -49.7 Total Exchange 289.3 -33.9 288.2 -90.1

Table 1-18 Year 2012 Peak load condition: Kosovo Power Losses With 400kV KS-AL Without 400kV KS-AL

P Q P Q Kosovo Power Losses (MW) (MVAr) (MW) (MVAr)

Total Losses of 400 kV lines 2.9 -67.8 2.9 -23.8 Total Losses of 220 kV lines 2.9 -9.0 3.7 -3.4 Total Losses of 110 kV lines 16.0 17.2 16.6 19.3 Total transmission line Losses 21.8 -59.6 23.3 -7.9 Total Transformer Losses 9.9 64.7 10.0 271.3 Total Losses of Transmission Network 31.6 205.2 33.3 263.3

Table 1-19 Year 2012 Peak load condition: Total Power Losses With 400kV KS-AL Without 400kV KS-AL

P Q P Q Total Power Losses (MW) (MVAr) (MW) (MVAr)

Total Losses of 750 kV lines 4 -1,100 4 -1,099 Total Losses of 400 kV lines 576 -14,116 579 -13,944 Total Losses of 220 kV lines 243 -1,672 246 -1,650 Total Losses of 150 kV lines 430 -2,508 430 -2,506 Total Losses of 120 kV lines 11 41 11 41 Total Losses of 110 kV lines 368 -1,238 370 -1,232 Total Losses of 35 kV lines 0 1 0 1 Total transmission line Losses 1,632 -20,592 1,640 -20,389 Total Transformer Losses 243 12,323 243 12,341 Total Transmission Network Losses 1,874 -8,269 1,883 -8,048



Figure 1-7 Year 2012 Case with no 400 kV line KS-AL Power flows in SEE network during peak load condition.

1.4.2.2.2 Light load conditions Load flow in normal conditions A summary of load flow calculation is reported in the following, comparing the results with the case where the 400 kV line is in operation.

The power exchanges with neighboring countries are reported in Table 1-20 and the power flows in the main interconnection lines of SEE transmission network and the total import / export of each country are given in Figure 1-8.

Transmission power losses of Kosovo and overall transmission losses of the modeled SEE system are reported in



Table 1-21 and Table 1-22. The presence of the line has decreased the power losses for Kosovo and for the entire region respectively by 0.9 MW and 3.5 MW. Table 1-20 Year 2013 Light load condition : Energy Exchanges


(MW) (MVAr) (MW) (MVAr) Exchange with Albania 228.6 -35.7 73.2 -11.8 Exchange with Serbia -41.4 -34.6 8.7 -31.6 Exchange with Macedonia 273.7 23.8 325.5 18.2 Exchange with Montenegro 140.2 -40.1 192.8 -51.3 Total Exchange 601.1 -86.6 600.2 -76.5



Table 1-21 Year 2013 Light load condition: Kosovo Power Losses With 400kV KS-AL Without 400kV KS-AL


Total Losses of 400 kV lines 1.6 -84.8 1.4 -36.8 Total Losses of 220 kV lines 0.8 -23.2 1.3 -22.7 Total Losses of 110 kV lines 1.4 -29.8 1.8 -29.9 Total transmission line Losses 3.7 -137.7 4.5 -89.3 Total Transformer Losses 4.8 108.6 4.9 112.1 Total Losses of Transmission Network 8.5 -29.2 9.4 22.8

Table 1-22 Year 2013 Light load condition: Total Power Losses With 400kV KS-AL Without 400kV KS-AL

P Q P Q Total Power Losses

(MW) (MVAr) (MW) (MVAr) Total Losses of 750 kV lines 2 -1,078 2 -1,078 Total Losses of 400 kV lines 303 -15,324 304 -15,155 Total Losses of 220 kV lines 88 -2,664 90 -2,648 Total Losses of 150 kV lines 267 -3,100 267 -3,097 Total Losses of 120 kV lines 12 41 12 41 Total Losses of 110 kV lines 92 -2,210 92 -2,204 Total Losses of 35 kV lines 0 0 0 0 Total transmission line Losses 763 -24,335 767 -24,141 Total Transformer Losses 141 6,353 141 6,355 Total Transmission Network Losses 904 -17,982 908 -17,786

Figure 1-8 Year 2013 Case with no 400 kV line KS-AL Power flows in SEE network during light load condition.

1.4.2.3 Year 2012 Conclusion As a starting year, the network situation of 2012-2013 was analyzed from point of view of line and equipment loadings, accepted voltage levels, presence of eventually bottlenecks, excessive and unjustified losses, eventually violation of generation capability limits (especially reactive), etc. performing load flows calculation for two



typical load conditions. No particular problems worth to be mentioned ware found during normal operating conditions.

The introduction of new 400kV Kosovo C Kashar (AL) has improved the voltage profile in Albania and has decreased the power losses not only in Kosovo but also in the region.

The connection of new TPP Kosovo C with local 220 kV network has improved the distribution of power flows in transmission network. The loadings of 400/220 kV autotransformers of Kosovo C are 25% during peak hours so in 2012 it can be installed only one of them.

Due to the introduction of 400/110 kV Peja 3 substation some neigboring 110 kV lines in the area are fully loaded during peak load conditions. It is recommended to reinforce the connection of 110 kV between Peja 1 and Peja 2 substations.



1.4.3 Analysis of steady-state conditions of the year 2014 The year 2014 was assumed as the year when the second unit of new TPP Kosovo C (Option 1) will be put into operation. Peak and light load conditions were analyzed.

System configuration The configuration of the transmission system is the same as in 2012 and the 400 kV, 220 kV, and 150/110 kV networks of each national transmission system has been considered. Load flow analyses were performed for the three Variants of the connection of TPP Kosovo C in transmission network.

In order to compare the role of the new 400 kV line Kosovo C (KS) - Kashar(AL), two variant are analyzed:

New 400 kV line Kosovo C (KS) Kashar (AL) is in operation in 2014; New 400 kV line Kosovo C (KS) Kashar (AL) is not in service in 2014; The KOSTT has provided the data of the planned configuration of Kosovo transmission network (220kV and 110 kV). In order to resolve some loading problems of the 110 kV network, the Consultant has proposed some reinforcement. Majority of proposed reinforcement are not related to the construction of new TPP Kosovo C, but became necessary due to growth of the load in some areas and increase of power injection from 400/110 kV Peja 3 substation. Of course further investigation should be performed during activities of transmission network planning in order to obtaine optimal solution for development of national transmission network. In the following are given the reinforcement of 110 kV network:

Reinforcement of 110 kV connection between substations of Prizren 1 and Prizren 2;

Reinforcement of 110 kV connection between substations of Kosovo A and Vushtria;

Reinforcement of 110 kV connection between substations of Peja 3 and Peja 1 and Peja 2;

1.4.3.1 Year 2014 Network configuration with the 400 kV line Kosovo C (KS) - Kashar(AL)

1.4.3.1.1 Peak load conditions Generation Dispatch Power dispatch of generation units in Kosovo (gross generation) for the peak load conditions is given in



Table 1-23.



Table 1-23 Winter 2014 Generation dispatch in Kosovo Pg Qg Power Plant MW Mvar

Ujmani 30 16Kosovo A3 126 59Kosovo A4 167 61Kosovo A5 167 61Kosovo B1 300 120Kosovo B2 300 120Kosovo C1 530 165Kosovo C2 520 164Total 2,140 766





Montenegro 50 50Serbia 0

Croatia & Slovenia 0 100 100 250 750 1,200Total 650 0 700 300 300 750 2,700

Load flow in normal conditions The complete analysis of N situations has been carried out for peak load conditions. No line or transformer overloads have been detected and the voltage profile is within normal limit values. Some main results are presented in Table 1-25 and



Table 1-26 for Kosovo power system.

The voltage profile and power flows in Kosovo transmission network and in the main 400 kV lines of the regional transmission network are illustrated in Figures A3.7 and in Figure A3.8 in Annex 3. A summary is given in Figure 1-9 indicating the active power flows in the main interconnection lines of SEE transmission network and the total import / export of each country. Table 1-25 Year 2014 Peak load condition: Energy Exchanges

Transit Losses Active Power

Reactive Power Active Reactive Power Supply

(MW) (MVAr) (MVAr) (MVAr) Generation Kosovo 2,140 766 Exchange with Albania 239.8 -26.5 1.4 -28.6 Exchange with Serbia -17.6 49.8 0.5 -21.8 Exchange with Macedonia 337.8 10.0 0.5 -12.0 Exchange with Montenegro 100.3 -55.0 0.2 -14.5 Total Exchange 660.3 -21.7 2.5 -76.8



Table 1-26 Year 2014 Peak load condition: Power Losses


(MW) (MVAr) (MW) (MVAr) (MW) (MVAr) Total Losses of 400 kV lines 3.5 -60.2 3.5 -55.9 3.5 -59.5 Total Losses of 220 kV lines 4.6 2.6 4.5 2.5 4.7 2.2 Total Losses of 110 kV lines 18.9 26.0 18.9 26.0 18.9 26.0 Total transmission line Losses 27.0 -31.7 27.0 -27.4 27.1 -31.4 Total Transformer Losses 12.3 362.2 12.3 361.6 12.3 361.6 Total Losses of Transmission Network 39.3 330.5 39.3 334.2 39.4 330.2

Figure 1-9 Year 2014 Power transits in SEE network during peak load condition.

1.4.3.1.2 Light load conditions Generation Dispatch Table 1-27 reports the generation dispatch (gross generation) for the Kosovo system for the light load conditions. Table 1-27 Summer 2015 Generation dispatch in Kosovo


Ujmani 8 7Kosovo B1 245 39Kosovo B2 245 39Kosovo C1 500 53Kosovo C2 500 53Total 1,498 191



Power Exchange Scenarios The scenario of power exchanges in summer light load condition between SEE countries is reported in Table 1-28. Table 1-28 Year 2015 Power Exchanges Scenario in summer minimum in SEE




Montenegro 50 100 150Serbia 150 150 300

Croatia & Slovenia 150 300 250 700Total 950 100 450 450 0 250 2,200

Load flow in normal conditions The load flow calculation was carried out based on the projected minimum demand and network configuration in 2014. The complete analysis of N situations has been carried out and no line or transformer overloads have been detected and the voltage profile is within normal limit values. Some main results are presented in Table 1-29 and Table 1-30 for Kosovo power system. Table 1-29 Year 2015 Light load condition: Energy Exchanges



(MW) (MVAr) (MVAr) (MVAr) Generation Kosovo 1,498 75 Exchange with Albania 316.2 -30.2 1.1 -35.6 Exchange with Serbia 81.1 -61.3 0.2 -24.1 Exchange with Macedonia 338.8 24.6 0.4 -13.4 Exchange with Montenegro 206.3 -42.2 0.6 -13.2 Total Exchange 942.4 -109.1 2.3 -86.3

Table 1-30 Year 2015 Light load condition: Power Losses Variant 1 Variant 2 Variant 3

P Q P Q P Q Power Losses (MW) (MVAr) (MW) (MVAr) (MW) (MVAr)

Total Losses of 400 kV lines 2.8 -72.6 2.8 -67.5 2.7 -71.6Total Losses of 220 kV lines 1.4 -18.3 1.4 -20.1 1.6 -20.4Total Losses of 110 kV lines 2.3 -26.3 2.6 -27.2 2.5 -27.5Total transmission line Losses 6.6 -117.3 6.9 -114.9 6.9 -119.5Total Transformer Losses 6.5 168.0 6.6 171.8 6.6 170.1 Total Losses of Transmission Network 13.0 50.7 13.4 56.9 13.4 50.6

A summary of results is given in Figure 1-10 indicating the active power flows in the main interconnection lines of SEE transmission network and the total import / export of each country.



Figure 1-10 Year 2015 Power transits in SEE network during light load condition.

1.4.3.2 Year 2014 Network configuration without the 400 kV line Kosovo C (KS) Kashar (AL)

1.4.3.2.1 Peak load conditions Load flow in normal conditions The voltage profile and power flows in Kosovo transmission network and in the main 400 kV lines of the regional transmission network are illustrated in Figures A3.9 and A3.10 in Annex 3. A summary of load flow calculation is reported in the following comparing the results with the case where the 400 kV line is in operation.

The power exchanges with neighboring countries are reported in Table 1-31. Table 1-31 Year 2014 Peak load condition : Energy Exchanges


(MW) (MVAr) (MW) (MVAr) Exchange with Albania 238.2 -26.7 2.5 -52.5 Exchange with Serbia -17.5 51.2 46.5 33.7 Exchange with Macedonia 335.6 9.2 417.3 -1.8 Exchange with Montenegro 104.0 -54.1 181.9 -49.4 Total Exchange 660.3 -20.4 648.2 -70.0

Transmission power losses of Kosovo and overall transmission losses of the modeled SEE system are reported in



Table 1-32and Table 1-33. The introduction of the line has decreased the power losses for Kosovo and for the entire region respectively by 2.4 MW and 16.3 MW.



Table 1-32 Year 2014 Peak load condition: Kosovo Power Losses With 400kV KS-AL Without 400kV KS-AL


Total Losses of 400 kV lines 3.5 -59.5 3.3 -19.8 Total Losses of 220 kV lines 4.7 2.2 6.1 11.5 Total Losses of 110 kV lines 18.9 26.0 19.9 29.3 Total transmission line Losses 27.1 -31.4 29.4 21.0 Total Transformer Losses 12.3 361.6 12.4 370.0 Total Losses of Transmission Network 39.4 330.2 41.8 391.0

Table 1-33 Year 2014 Peak load condition: Total Power Losses

With 400kV KS-AL Without 400kV KS-AL P Q P Q Total Power Losses

(MW) (MVAr) (MW) (MVAr) Total Losses of 750 kV lines 4 -1,098 4 -1,098 Total Losses of 400 kV lines 602 -13,585 607 -13,388 Total Losses of 220 kV lines 261 -1,550 266 -1,512 Total Losses of 150 kV lines 465 -2,277 465 -2,273 Total Losses of 120 kV lines 12 45 12 45 Total Losses of 110 kV lines 408 -1,103 412 -1,091 Total Losses of 35 kV lines 0 1 0 1 Total transmission line Losses 1,751 -19,568 1,767 -19,316 Total Transformer Losses 257 13,069 258 13,102 Total Transmission Network Losses 2,008 -6,499 2,024 -6,214

The power flows in the main interconnection lines of SEE transmission network and the total import / export of each country are given in Figure 1-11. It can be observed that the power transited by the line is now equally shared by the 400 kV lines of Montenegro and Macedonia.

Figure 1-11 Year 2014 Case with no 400 kV line KS-AL: Power flows in SEE network during peak load condition.



1.4.3.2.2 Light load conditions Load flow in normal conditions A summary of load flow calculation is reported in the following comparing the results with the case where the 400 kV line is in operation.

The power exchanges with neighboring countries are reported in Table 1-34 and the power flows in the main interconnection lines of SEE transmission network and the total import / export of each country are given in Figure 1-10. Table 1-34 Year 2015 Light load condition : Energy Exchanges


(MW) (MVAr) (MW) (MVAr) Exchange with Albania 316.2 -30.2 107.7 -11.7 Exchange with Serbia 81.1 -61.3 147.7 -56 Exchange with Macedonia 338.8 24.6 406.3 24.7 Exchange with Montenegro 206.3 -42.2 278.9 -49.1 Total Exchange 942.4 -109.1 940.6 -92.1

Transmission power losses of Kosovo and overall transmission losses of the modeled SEE system are reported in Table 1-35and Table 1-36. The introduction of the line has decreased the power losses for Kosovo and for the entire region respectively by 1.8 MW and 5.7 MW. Table 1-35 Year 2015 Light load condition: Kosovo Power Losses

With 400kV KS-AL Without 400kV KS-AL P Q P Q Kosovo Power Losses

(MW) (MVAr) (MW) (MVAr) Total Losses of 400 kV lines 2.8 -72.6 2.7 -26.8 Total Losses of 220 kV lines 1.4 -18.3 2.5 -14.7 Total Losses of 110 kV lines 2.3 -26.3 3.0 -25.8 Total transmission line Losses 6.6 -117.3 8.1 -67.2 Total Transformer Losses 6.5 168.0 6.6 175.8 Total Losses of Transmission Network 13.0 50.7 14.8 108.5

Table 1-36 Year 2015 Light load condition: Total Power Losses With 400kV KS-AL Without 400kV KS-AL

P Q P Q Total Power Losses (MW) (MVAr) (MW) (MVAr)

Total Losses of 750 kV lines 2 -1,077 2 -1,076 Total Losses of 400 kV lines 311 -15,049 314 -14,861 Total Losses of 220 kV lines 90 -2,617 93 -2,590 Total Losses of 150 kV lines 291 -2,902 292 -2,895 Total Losses of 120 kV lines 11 39 11 39 Total Losses of 110 kV lines 98 -2,148 99 -2,139 Total Losses of 35 kV lines 0 0 0 0 Total transmission line Losses 804 -23,753 811 -23,523 Total Transformer Losses 147 6,736 147 6,745 Total Transmission Network Losses 950 -17,016 958 -16,778

1.4.3.3 Year 2014 Conclusion The transmission network situation of 2014-2015 was analyzed from point of view of line and equipment loadings, accepted voltage levels, presence of eventually bottlenecks, excessive and unjustified losses, eventually violation of generation capability limits (especially reactive), etc. performing load flows calculation for two typical load conditions.



Figure 1-12 Year 2015 Case with no 400 kV line KS-AL Power flows in SEE network during light load condition. No particular problems regarding the bulk transmission system (400 kV and 220 kV) in the region ware found during normal operating conditions. Some low voltage levels have been detected in south and northeast parts of Albania namely during peak load. The problem is resolved on local basis, by coordination of reactive sources and by installation of adequate reactive compensation in Albania. It was observed that in these areas of Albania is missing not only an adequate voltage support, but also active generation and this problem can not be solved only with imports of energy from abroad.

The introduction of new 400kV Kosovo C Kashar (AL) has improved the voltage profile in Albania and has decreased the power losses not only in Kosovo but also in the region.

The connection of new TPP Kosovo C with local 220 kV network has improved the distribution of power flows in transmission network. The loadings of 400/220 kV autotransformers of Kosovo C are 40% during peak hours.

Due to the introduction of 400/110 kV Peja 3 substation some neigboring 110 kV lines in the area are fully loaded during peak load conditions. The increase of load on northen regions (Mitrovice, Vuitern, etc) of Kosovo has caused a full loading of the 110 kV lines upplying this area during peak load conditions. It is recommended to reinforce 110 kV connection of between Peja 3 and Peja 1, Peja 2 substations. Also dedicated planning studies shoud be performed to reinforce 110 kV network supplying northen area of Kosovo.



1.4.4 Analysis of steady-state conditions of the year 2016 The year 2016 was assumed as the year when the third unit 500 MW of new TPP Kosovo C (Option 1) will be put into operation. Peak and light load conditions were analyzed.

Also the Option 3 with the configuration 500 MW + 2x750 MW of the new TPP Kosovo C is analyzed.

System configuration The configuration of the transmission system takes in consideration the situation in 2015 of 400 kV, 220 kV, and 150/110 kV networks of each national transmission system. Load flow analyses were performed for the three Variants of the connection of TPP Kosovo C in transmission network.

According to result of the revised REBIS GIS study additional generation units are introduced to the model of the SEE system to match the increase of power demand in each country.

The same configuration of the national transmission network is considered for 110 kV including the proposed reinforcements relevant to years 2014-2015. Further investigation should be performed during activities of transmission network planning in order to obtaine optimal solution for development of national transmission network up to 2020. In order mitigate some loading problems of the 110 kV network, the Consultant has proposed some additional reinforcement. Majority of proposed reinforcement are not related to the construction of new TPP Kosovo C, but became necessary due to growth of the load in some areas and increase of power injection from 220/110 kV Ferizaj substation. In the following are given the reinforcement of 220 and 110 kV network:

Second transformer 150 MVA at 220/110 kV substation of Ferizaj 2;

Reinforcement of 110 kV connection between Ferizaj 2 Ferizaj 1 and Shtimje substations

1.4.4.1 Year 2016 Option 1 of new TPP Kosovo C: third unit 500 MW

1.4.4.1.1 Peak load conditions Generation Dispatch Power dispatch generation units in Kosovo (gross generation) for the peak load conditions is given in Table 1-37. Table 1-37 Winter 2016 Generation dispatch in Kosovo


Ujmani 30 16Kosovo A3 125 100Kosovo A4 160 100Kosovo A5 160 100Kosovo B1 290 101Kosovo B2 290 101Kosovo C1 530 140Kosovo C2 530 140Kosovo C3 530 140Total 2,645 937






Greece (& Italy) 300 450 750Macedonia 150 150 50 350

Montenegro 150 150Serbia 0

Croatia & Slovenia 100 100 350 800 1,350Total 1,100 0 700 150 400 800 3,150

Load flow in normal conditions The load flow calculation was carried out based on the projected peak demand and network configuration in 2016.

The voltage profile and power flows in Kosovo transmission network and in the main 400 kV lines of the regional transmission network are illustrated in Figures A3.11 and A3.12 in Annex 3.

No line or transformer overloads have been detected and the voltage profile is within normal limit values. Some main results are presented in Table 1-39 and Table 1-40 for Kosovo power system. Table 1-39 Year 2016 Peak load condition: Energy Exchanges



(MW) (MVAr) (MVAr) (MVAr) Generation Kosovo 2,643 937 Exchange with Albania 355.0 -9.5 2.5 -16.5 Exchange with Serbia 81.0 22.9 0.6 -20.6 Exchange with Macedonia 477.6 -10.5 0.9 -7.0 Exchange with Montenegro 188.1 -31.6 0.5 -12.0 Total Exchange 1,101.7 -28.7 4.5 -56.1

Table 1-40 Year 2016 Peak load condition: Power Losses Variant 1 Variant 2 Variant 3

P Q P Q P Q Power Losses (MW) (MVAr) (MW) (MVAr) (MW) (MVAr)

Total Losses of 400 kV lines 6.4 -36

tpp task 2 transmission system impact assesment

Documents

transmission network

kv transmission system

related transmission

generation system

reconstruction pyrycesi

transmission expansion

task report

consortium members